This invention relates to a degassing assembly for removing bubbles from a sample of an electroless plating solution, and more particularly, to a degassing assembly adapted to effectively remove a great volume of hydrogen gas or bubbles from a bubbly sample of an electroless plating solution in order to ensure precise measurement when it is intended to automatically control the concentration and/or the amount of reaction by-products of an electroless plating solution by continuously and automatically measuring the concentration, for example, of a metal ion, and/or the property, for example, specific gravity, conductivity or refractive index of an electroless plating solution.
In analyzing some components in an electroless plating solution, inclusion of bubbles in the solution causes incorrect sampling. If the solution containing bubbles is supplied to an analyzer without degassing, bubbles in the solution disturb the analysis to give rise to a noise. For example, an electroless nickel plating solution is continuously monitored for nickel ion concentration by means of an analyzer such as a spectrophotometer. If an electroless nickel plating solution which contains a great volume of hydrogen gas due to the reaction involved is sampled and introduced into an analyzer without degassing, gas bubbles tend to develop noises, resulting in unacceptable analysis results.
A typical example of the known degassing means for analytical use with plating solutions is shown in FIG. 1. This degassing means comprises a vertical pipe 1 through which liquid flows upwards and a branch pipe 2 connected to the vertical pipe 1 at right angles. Bubbles are mainly entrained with the upward flow of liquid flowing vertically upwards through the vertical pipe 1 while a portion of the liquid entering the branch pipe 2 from which the portion of the liquid is led to an analyzer is more or less free of bubbles. Such a degassing means, however, is not satisfactorily effective for liquids containing a great volume of bubbles, for example, electroless nickel plating solutions, and a considerable volume of bubbles is entrained in the liquid flow through the branch pipe 2 and led to an analyzer. Therefore, the analytical results have considerably unacceptable noises due to the bubbles.